As President-elect Donald Trump threatens to “repeal and replace” the Affordable Care Act that provides health care to millions, supporters of Covered California are joining forces to come up with ways to defend the public health exchange they’ve spent the last five years building.

At a well-attended meeting Thursday, the Covered California board said it is continuing to push ahead with open enrollment, which ends Jan. 31 for people changing their coverage within the exchange or gaining coverage for the first time, despite the program’s uncertain future.

California was the first state to open a public health exchange under the Affordable Care Act, and many Covered California supporters consider the program a model for the nation. About 1.3 million people are insured through Covered California plans, which offer subsidies for enrollees based on their age, pre-existing conditions, geographic location and income level.

If the Trump administration were to repeal the Affordable Care Act entirely, that would leave 7.5 million Californians uninsured by 2021, according to a recent study by the Urban Institute and the Robert Wood Johnson Foundation. On Thursday, representatives of the California Primary Care Association, the California Association of Health Plans and other groups took turns at the microphone, each promising to stand by Covered California as it enters uncertain waters.

Still, just nine days after the election, speakers didn’t yet know how the state health plan would be challenged, and how they could respond.

State Sen. Ed Hernandez, D-West Covina, who’s the chair of the Senate Health Committee, said the possible loss of federal subsidies for Medicaid “would strike a catastrophic blow to the state” but vowed to “fight against any effort to take that funding away.” He didn’t specify, however, what actions he would take.

“To Californians who are newly shopping or reevaluating – we stand ready to fight to keep what is working in this state,” he said. “What we have is too important to lose. … Any rollback of the progress that’s been made in this state would destabilize the market for the uninsured.”

Panelists said any repeal of federal health care reform would likely not take effect until 2018, as the legislation required for that restructuring would need to move through the legislative process. Larry Levitt, vice president for special initiatives at the Kaiser Family Foundation, said Covered California defenders will need to first answer a few important questions.

“Are there resources for a state to go forward if it so chooses?” he asked. “If California wants to preserve the gains it’s made, is there the money and flexibility under an alternative approach to do that? Is there a role for an organization like Covered California?”

Many speakers said any answers would have to wait until Trump and House Speaker Paul Ryan clarified their vision for the health reform law.

In the meantime, Covered California proponents are looking to improve current plans, such as clarifying special enrollment period and third party payment rules, as well as continuing to combat high prescription drug prices.

The speakers acknowledged the recent 13 percent jump in Covered California premium costs and said they would set out to work with partner plans to keep such premium hikes in check while continuing to serve enrollees.

“I’ve been very adamant about not speculating about what will happen, but still I felt it was important to have this forum,” said Diana Dooley, the state’s health and human services secretary and chairwoman of the Covered California board. “We do have contracts through 2017, and we intend to respect those contracts as far as the law allows. This didn’t start in 2010. It was a long time coming to the conditions we were facing then. I look forward to engaging with the advisers we have with us today on their perspectives as we work over the next weeks and months.”